The invention relates to a cooling system for a liquid-cooled combustion engine having at least a radiator with at least one inlet and one outlet, at least one coolant pump and at least one device, hereafter referred to as control valve, for controlling the flow of coolant through the radiator depending, if so desired, on the coolant temperature.
Such a cooling system is applied on a large scale especially on combustion engines in motor vehicles. The operating principle of such a cooling system generally is as follows: (see FIG. 1). When the combustion engine is running, heat is generated. This heat is carried off by a coolant circulating through the wall of the combustion engine. The coolant is circulated by a coolant pump (2). To allow rapid warm-up of the engine, the coolant circuit is divided into two loops which may be interconnected by means of one or more control valves (3). In a first loop, (10), (11) and (12) the coolant circulates through the cylinder block only. The second loop (13 and 14) is opened only when the coolant temperature exceeds a predetermined value. The second loop passes coolant through the radiator 7 and is opened by means of control valve (3) so that the heat generated can be carried off through the radiator (4). The radiator is made up of a heat exchanger (5) and end covers (6) and (7). Generally, the radiator is a heat exchanger of the liquid/air type situated at some distance from the engine, with the heat generated being swept away by the air through which the vehicle moves or by a forced air flow produced by a fan.
The coolant circulation pump (2) is usually mounted on the engine and is driven by the crankshaft of the combustion engine by means of, for instance, a V-belt, timing chain or a train of gears. This pump arrangement is advantageous in that use may be made of the mechanical energy generated in the combustion engine. It has a disadvantage, however, in that the pump operates only when the engine is running and that the pump capacity varies with the speed of the engine. A further disadvantage is that, being directly mounted on the engine, the pump must be capable of withstanding high temperatures and, for that reason, must be made of metal and the seals must meet stringent requirements. These factors increase cost. The same applies to the control valve.